[elektro-etc] nuklearis eromu - reloaded

[Levente Móczó]

Több dolog teljesen bizonyságos:
Én nem értek a tórium reaktorokhoz.
HZS legalább az alapjaival tisztában van.
Ezért linkeltem az Ő írását.
Valóban szkeptikus, igen.
De legyen igazatok, legyen úgy, hogy nincs akadálya az ilyen (tórium,
fúziós) erőművek megvalósításának.
Mi kell az elinduláskhoz akkor?
Elhatározás, és a beindításukhoz szükséges energia.
Elhatározás a fasorban sincsen.
A beindításukhoz szükséges energia ebben a pillanatban a rendelkezésünkre áll.
Csak épp, ha ezt kivesszük a működő rendszerből, akkor azok, akiknek
emiatt kevesebb jutott, roppant morcosak lesznek :)


A lenti dokukat egy régi hozzászólásból ollóztam, előfordulhat, hogy
vannak benne idejétmúlt dolgok:
pp. 132-135 MANKIND AT THE TURNING POINT: The Second Club of
Rome Report, by Mihajlo Mesarovic and Eduard Pestel; E.P.
Dutton, 1974:
--------------

Assume, as the technology optimists want us to, that in one
hundred years all primary energy will be nuclear. Following
historical patterns, and assuming a not unlikely quadrupling of
population, we will need, to satisfy world energy requirements,
3000 "nuclear parks" each consisting of, say, eight
fast-breeder reactors. The eight reactors, working at 40
percent efficiency, will produce 40 million kilowatts of
electricity collectively. Therefore, each of the 3000 nuclear
parks will be converting primary nuclear power equivalent to
100 million kilowatts thermal. The largest nuclear reactors
presently in operation convert about 1 million kilowatts
(electric), but we will give progress the benefit of doubt and
assume that our 24,000 worldwide reactors are capable of
converting 5 million kilowatts each. In order to produce the
world's energy in one hundred years, then, we will merely have
to build, in each and every year between now and then, four
reactors per week! And that figure does not take into account
the lifespan of nuclear reactors. If our future nuclear
reactors last an average of thirty years, we shall eventually
have to build about two reactors per day simply to replace
those that have worn out. The implications of such a
development in the Developed World will be even more
pronounced, as it is shown in the case of the United States in
Fig. 10.1. ( By 2025, sole reliance on nuclear power would
require more than 50 major nuclear installations, on the
average, in every state in the union. )

For the sake of this discussion, let us disregard whether this
rate of construction is technically and organizationally
feasible in view of the fact that, at present, the lead time
for the construction of much smaller and simpler plants is
seven to ten years. Let us also disregard the cost of about
$2000 billion per year -- or 60 percent of the total world
output of $3400 billion -- just to replace the worn-out
reactors and the availability of the investment capital. We may
as well also assume that we could find safe storage facilities
for the discarded reactors and their irradiated accessory
equipment, and also for the nuclear waste. Let us assume that
technology has taken care of all these big problems, leaving us
only a few trifles to deal with.

In order to operate 24,000 breeder reactors, we would need to
process and transport, every year, 15 million kilograms of
plutonium-239, the core material of the Hiroshima atom bomb.
(Only ten pounds of the element are needed to construct a
bomb.) As long as it is not inhaled or otherwise introduced
into the bloodstream of human beings, plutonium-239 can be
safely handled without any significant radiological hazards.
But if it is inhaled, ten micrograms * of plutonium-239 is
likely to cause fatal lung cancer. A ball of plutonium the size
of a grapefruit contains enough poison to kill nearly all the
people living today. Moreover, plutonium-239 has a radioactive
life of more than 24,000 years. Obviously, with so much
plutonium on hand, there will be a tremendous problem of
safeguarding the nuclear parks -- not one or two, but 3000 of
them. And what about their location, national sovereignty, and
jurisdiction? Can one country allow inadequate protection in a
neighboring country, when the slightest mishap could poison
adjacent lands and populations for thousands and thousands of
years? And who is to decide what constitutes adequate
protection, especially in the case of social turmoil, civil
war, war between nations, or even only when a national leader
comes down with a case of bad nerves. The lives of millions
could easily be beholden to a single reckless and daring
individual.
---------------

http://dieoff.com/page155.htm :

In June, France said it would scrap the highly controversial
Superphenix nuclear fast-breeder, saying it was too costly and of
doubtful value.

Britain, the United States and Germany have already abandoned their
programs for similar reasons.

The state-owned Power Reactor and Nuclear Fuel Development Corp (PNC),
the operator of Japan's fault-prone prototype fast- breeder reactor
Monju, also came under criticism in the report for accidents and
cover-ups.

-------------------------

http://www.feasta.org/documents/energy/nuclear_power.htm :

There are three fastbreeder rectors in the
world:
Beloyarsk-3 in Russia, Monju in Japan and Ph´nix in France; Monju
and Ph´nix have long been out of operation; Beloyarsk is still operating, but
it has never bred. But let us look on the bright side of all this. Suppose
that, with 30 years of intensive research and development, the world
nuclear power industry could find a use for all the reactor-grade plutonium in
existence, fabricate it into fuel rods and insert it into newly-built fast-
breeder reactors - 80 of them, plus a few more, perhaps, to soak up some of
the plutonium that is being produced by the ordinary reactors now in
operation. So: they start breeding in 2035. But the process is not as fast as
the name suggests ("fast" refers to the speeds needed at the subatomic
level, rather than to the speed of the process). Forty years later, each breeder
reactor would have bred enough plutonium to replace itself and to start up
another one. By 2075, we would have 160 breeder reactors in place. And that
is all we would have, because the ordinary, uranium-235-based reactors
would by then be out of fuel.
...
Thorium

The other way of breeding fuel is to use thorium. Thorium is a
metal found in most rocks and soils, and there are some rich ores bearing as
much as 10 percent thorium oxide. The relevant isotope is the slightly
radioactive thorium-232. It has a half-life three times that of the earth, so
that makes it useless as a direct source of energy, but it can be used
as the starting-point from which to breed an efficient nuclear fuel.
Here's how:
* Start by irradiating the thorium-232, using a start-up fuel -
plutonium-239 will do. Thorium-232 is slightly fertile, and absorbs
a neutron to become thorium 233.
* The thorium-233, with a half-life of 22.2 minutes, decays to protactinium-233.
* The protactinium-233, with a half-life of 27 days, decays into uranium-233.
* The uranium-233 is highly fissile, and can be used not just as
nuclear fuel, but as the start-up source of irradiation for a blanket
of thorium-232, to keep the whole cycle going indefinitely. But, as is
so often the case with nuclear power, it is not as good
as it looks. The two-step sequence of plutonium breeding is, as we have
seen, hard enough. The four-step sequence of thorium-breeding is worse. The
uranium-233 which you get at the end of the process is contaminated with
uranium-232 and with highlyradioactive thorium-228, both of which are neutron-
emitters, reducing its effectiveness as a fuel; it also has the disadvantage
that it can be used in nuclear weapons. The comparatively long
half-life of protactinium-233 (27 days) makes for problems in the
reactor, since substantial quantities linger on for up to a year. Some
reactors -
including Kakrapar-1 and -2 in India - have both achieved full power using
some thorium in their operation, and it may well be that, if there is to
be a very long-term future for nuclear fission, it will be thorium that
drives it along. However, the full thorium breeding cycle, working on a scale
which is largeenough and reliable-enough to be commercial, is a long way
away.

For the foreseeable future, its contribution will be tiny. This is
because the cycle needs some source of neutrons to begin. Plutonium could
provide this but (a) there isn't very much of it around; (b) what
there is (especially if we are going to do what Lovelock urges) is
going to
be busy as the fuel for once-through reactors and/or or fast-breeder
reactors, as explained above; and (c) it is advisable, wherever there is an
alternative, to keep plutonium-239 and uranium-233 - an unpredictable and
potentially incredibly dangerous mixture - as separate as possible. It follows
that thorium reactors must breed their own start-up fuel from uranium-
233. The problem here is that there is practically no uranum-233 anywhere in
the world, and the only way to get it is to start with (say) plutonium-
239 to get one reactor going. At the end of forty years, it will have bred
enough uranium-233 both to get another reactor going, and to replace the
fuel in the original reactor. So, as in the case of fastbreeders, we
have an estimated 30 years before we can perfect the process enough to
get
it going on a commercial scale, followed by 40 years of breeding. Result: in
2075, we could have just two thorium reactors up and running.